I can't answer most of your questions - other than the last one - about inherent risks, at least from my perspective!
I have a small intracanicular tumor. As I have learned, these are one of the better ones to have because they typically grow slower than the CPA tumors and are by their location the furthest from the brainstem, so cause the least 'serious' damage - i.e.impingement on the brain stem. I am encouraged to hear you have such a large tumor and that it is still all intracranicular.
I am hoping to stay w&w for a very long time. I am practically asymptomatic - or at least the AN symptoms are so mild they don't slow me down (mild hearing loss and temporary/intermittent balance/light-headedness issues). I have spoken to my ENT several times - he is a proponent of w&w and has not told me of any inherent risks with watching & waiting. He suggested my tumor could get to 1.5cm outside extra-canicular and still be in watch & wait - i.e. since the tumor is all intracanicular, I haven't even gotten to the starting line yet. He views a typical AN tumor less than 1.5cm extracanicular no more difficult or risk to remove than a small tumor. He is not confident in consistently preserving hearing - so doesn't encourage hearing preservation surgery as its success rates are rather low. [ie. your wait for translab versus mid-fossa now - why risk hearing preservation surgery, when your hearing is good and the tumor is small/doing no harm.]
I also did have a consult with a GK surgeon - his reasoning was identical (other than he was anti-surgery). He suggested I wait until the tumor is much larger and my hearing has been substantially lost as GK will destroy hearing. His view - research seems much more positive on hearing preservation than the GK surgeon inferred - but will assume he is talking long term frames (maybe greater than 5 years). He thinks I could w&w for several years. AGain, his threshold for treatment for my type of tumor is probably closer to 1.5cm extracanicular (thus, again I haven't even reached the starting line).
My appointment with the neurosurgeon is June 3 - my first appointment - I was diagnosed in December so the Canadian medical system is a test of ones patience (but at least shows how non-critical my situation truly is - and I recognize that fact!) So, I will be interested to hear what he says. I will have had my second MRI at that point (6 mnths apart) which is May 21 so will have a clearer picture on whether this thing thinks it wants to grow.
Hope that answered at least one of your questions - I think the inherent risks of watching and waiting for the typical slow growing intracanciular tumor are very low and substantially out weight the risks of either surgery or radiation at this point. Obviously consistent 6 month or 12 month follow-ups will be required while we stay in this regime, but it is highly possible to ride the waves for several years. (My ENT thinks it is possible that I may be w&w for at least 10 years, and maybe for the rest of my life!) I am 37 years old - so I expect to have a really long life yet.